NASA astronaut Mark Kelly is leaving the side of his wounded wife, Rep. Gabrielle Giffords, D-Ariz., at TIRR Memorial Hermann Hospital in Houston to deliver the closing prayer at the annual National Prayer Breakfast in the nation’s capital on Thursday.

Kelly, a U.S. Navy captain, will speak at the bipartisan event following remarks by President Obama.

Giffords is undergoing rehabilitation in Houston after being shot in the head during a gunman’s attack in Tucson on Jan. 8 that killed six and wounded 13, including Giffords.

Kelly tweeted on Wednesday that his wife was doing better.

“Today was a huge day for GG. Lots of progress!” Kelly wrote, without being specific.

Kelly is the only astronaut and active duty military officer married to a member of Congress.

As an astronaut, he has commanded one shuttle flight and flown on two other missions. He was originally scheduled to command the last shuttle mission tentatively scheduled in April before his wife’s injuries in the Tucson shooting.

Kelly’s brother, Scott, is also an astronaut, serving aboard the orbiting International Space Station.

The National Prayer Breakfast, first held in 1953, has been attended by every president. Speakers at the interfaith gathering focus on affirming commonly held religious values rather than delving into political differences.

The breakfast this year is chaired by Reps. Jeff Miller, R-Fla., and former Rep. Ann Kirkpatrick, D-Ariz.

Among the speakers will be José Enriquez, one of 33 men rescued last year from a collapsed mine in Chile.